Index: Include/Classes/System/Diagnostics/Trace.ab
===================================================================
--- Include/Classes/System/Diagnostics/Trace.ab	(revision 43)
+++ Include/Classes/System/Diagnostics/Trace.ab	(revision 44)
@@ -1,6 +1,48 @@
 Class Trace
+	Static IndentNum = 0 As Long
+
+	Static Function GetIndentString() As String
+		Dim i As Long
+		Dim ResultStr = ""
+		For i = 0 To ELM( IndentNum )
+			ResultStr = ResultStr + Ex"\t"
+		Next
+		Return ResultStr
+	End Function
 Public
+
+/*
+	TODO: 実装
+
+	' アサート表示
+	Static Sub Assert( condition As Boolean )
+		If condition == False then
+			'TODO: コールスタックを表示
+		End If
+	End Sub
+	Static Sub Assert( condition As Boolean, message As String )
+		If condition == False then
+			WriteLine( message )
+		End If
+	End Sub
+*/
+
+	' インデントレベルを上げる
+	Static Sub Indent()
+		IndentNum++
+	End Sub
+
+	' インデントレベルを下げる
+	Static Sub Unindent()
+		If IndentNum <= 0 Then
+			IndentNum = 0
+			Return
+		End If
+		IndentNum--
+	End Sub
+
+	' 一行の文字列を出力
 	Static Sub WriteLine( message As String )
-		Dim tempmsg = message + Ex"\n"
+		Dim tempmsg = GetIndentString() + message + Ex"\n"
 		OutputDebugString( tempmsg )
 	End Sub